And while you might assume that they have a lot of fun while making these movies, director James Gunn has revealed that two of its main players have never even stepped foot on set.
Vin Diesel and Bradley Cooper voice the dynamic duo Groot and Rocket. However, when Gunn posted a photo from the first day of filming for Guardians of the Galaxy Vol. 3, a number of eagle-eyed fans pointed out that they were missing from the line-up.
In response to one of the comments on his post, the director revealed: "Rocket's acting and motion capture is always done by @thejudgegunn [James' brother Sean Gunn]. The voice is done by Bradley.
"Neither Vin nor Bradley have ever been on a Guardians set."
Fans were quick to offer praise to the pair for their capabilities as voice actors.
In response to a Reddit post sharing Gunn's comment, one person wrote: "I feel like I appreciate Bradley Cooper's ability as a voice actor even more knowing this.
"He kills the role. You'd think he was visiting set quite often to get a feel for the context and vibes."
Another wrote: "I think it's cool that Cooper is able to put so much life into the character without having been on set with the other actors. Seems like there's so much chemistry with him."
Although a couple of people pointed out that Diesel gets paid millions for essentially saying 'I am Groot', one user replied: "Vin Diesel is the king of simple dialogue voicelines that will absolutely destroy your heart.
"'We are Groot' and 'Superman'. He deserved those millions."
Gunn confirmed the news that the anticipated threequel is well underway earlier this month.
It's scheduled for release on 5 May 2023, so it'll be a while before anything more comes out, but we can at least be safe in the knowledge that they're working on it.
As well as Cooper and Diesel, the all-star cast includes Chris Pratt, Zoe Saldaña, Dave Bautista, Karen Gillan, with the addition of Will Poulter as Adam Warlock.
The events of the third GOTG flick will be set after Avengers: Infinity War and Avengers: Endgame, and - if Gunn is to be believed - will wrap up this particular chapter of the Guardians saga.
Gunn himself was previously fired from the project after controversial tweets between 2008 and 2012 in which he joked about subjects such as rape and paedophilia emerged.
While he was later reinstated, Gunn said: "I have regretted [those jokes] for many years since.
"Regardless of how much time has passed, I understand and accept the business decisions taken today. Even these many years later, I take full responsibility for the way I conducted myself then.
"All I can do now [is offer] my sincere and heartfelt regret. To everyone inside my industry and beyond, I again offer my deepest apologies."
He was later reinstated in 2019, and seems pretty glad to be back in the hotseat for the next instalment.
Words: Daisy Phillipson